Caponata is the classic Sicilian antipasto that perfectly captures the bold flavors of the Mediterranean region. This sweet-sour relish is generally served at room temperature and combines eggplant, celery, capers, tomatoes, anchovies, and sometimes raisins. Caponata will keep for several days; indeed, it's often tastier on the second day. Serve it on slices of crusty bread, as a side dish with grilled meats, or on an antipasto platter.
Place the eggplant in a large colander and sprinkle with the salt. Cover with a kitchen towel, and place a plate on top of the eggplant. Weight the plate with several large cans and let the eggplant drain for 30 to 45 minutes. Rinse the cubes and pat dry with paper towels.
Place 1/3 cup of oil in a large skillet and heat until the oil is hot (but not smoking) over medium-high heat. Add half of the eggplant cubes and cook, turning occasionally, until the eggplant is golden brown on all sides and tender, 7 to 10 minutes. Transfer the eggplant to paper towels to drain. Repeat with another 1/3 cup oil and the remaining eggplant. Set aside at room temperature.
Place the remaining oil in the skillet and heat until the oil is hot (but not smoking) over medium-high heat. Add the onion and anchovies, and cook, stirring frequently, until the onions are soft and golden, about 10 minutes. Add the celery and tomatoes, and cook for 5 minutes, or until the tomatoes release their juices. Add the vinegar and sugar, and cook for 3 minutes. Lower the heat to medium-low and add the olives, capers, raisins (if using), and the reserved eggplant. Cook until hot.
Transfer the mixture to a platter and let cool to room temperature. Season to taste with salt and pepper. Refrigerate the caponata, covered, for up to one week. Return to room temperature before serving.